The present invention relates to systems, kits and methods for preparing a solid-fibrin web or autologous fibrin glue.
Fibrin glue is known to be a haemoderivative largely that is used as a topical surgical adhesive or an haemostatic agent. Several kits are available on the market that contain concentrated fibrinogen from donors, associated to a proteic activator of human or animal origin, such as thrombin or batroxobin, for obtaining heterologous fibrin glue.
Such known kits involve the use of material of human or animal origin, which, owing to its origin, could result in possible viral contamination and in serious risks for the receiver of the fibrin glue. In the past the authorities have been compelled to suspend from trade or even ban the haemoderivatives obtained by using material of human or animal origin. Furthermore, rejection cases are known from the literature resulting from reimplanting fibrin produced by using human or animal proteins in patients. Such cases are indeed due to the heterologous origin, with respect to the receiver organism, of the sealant protein being reimplanted or some of the components used for preparing it.
The autologous fibrin glue, i.e. fibrin glue autologously obtained from a patient's own blood, is more reliable with respect to the rejection and/or infection risks. Several procedures have already been described for obtaining extemporary autologous fibrin glue, but no “ready to use” kit is available on the market although some relevant references can be found in the patent literature.
U.S. Pat. No. 5,733,545 discloses a plasma-buffy coat concentrate to be combined with a fibrinogen activator to form a platelet glue wound sealant. The method disclosed in this patent allows for a patient's blood to be processed in order to obtain autologous fibrin glue, but the methods use thrombin or batroxobin as the fibrinogen activator. These activators are of human or animal nature and therefore still involve the risk of rejection and/or viral infections for the patient.
U.S. Pat. No. 5,555,007 discloses a method and an apparatus for making concentrated plasma to be used as a tissue sealant. The method consists in separating plasma from whole blood and removing water from said plasma by contacting it with a concentrator to provide concentrated plasma which can be thereafter coagulated with a solution containing thrombin and calcium. The apparatus comprises a first centrifuge separator in a first chamber, a concentrator (e.g. dextranomer or polyacrylamide) included in a second chamber communicating with the first chamber, and a second separator. The method disclosed in this reference requires a long time for obtaining the plasma concentrate necessary for the subsequent preparation of autologous fibrin glue and the apparatus is expensive and not disposable. The method does not disclose using a calcium-coagulation activator, and requires a pre-concentration step.
Many methods and systems require the transfer of a fluid from one container to another. For example, many chemical and medical devices require the transfer of a requisite volume of liquid to be reacted sequentially with various reagents and specific volumetric aliquots. A common practice is to remove closures on two containers and to pipette liquid in one container to the other. This practice, however, exposes the sample to environmental contaminants. For example, this technique is used to transfer plasma that has been separated from red blood cells in a blood sample. A special technique is required, however, to remove the plasma at the interface meniscus. Frequently the high-density, undesirable, lower-fraction red blood cells contaminate the aspirated sample. To avoid this problem, the pipette is frequently maintained a safe distance from the meniscus (i.e. the separator between the plasma and red blood cells), thereby resulting in an incomplete transfer of the sample. The incomplete transfer of the desirable fraction results in lower than optimum volume yield and non-stoichiometric ratios of the sample reagents and those in the second container. This second condition can be a serious source of performance variation of the product. This is the case in many enzyme reactions in which reaction rates are a maximum at certain stoichiometric ratios and rapidly diminish at higher or lower ratios.
Wound care is one of the most important issues in medicine, especially with respect to chronic ulcers, fistulae, etc. This issue is important not only because of the high cost of management, but also because of the low success rate. Other problems associated with wound care and burn care include loss of liquids and the possibility of infections occurring. Synthetic or animal-origin membranes have been used to separate bone cavities from soft tissues in the process of re-ossification.
One treatment for wound care may include applying biological tissues or sponges (generally protein based) of animal origin, e.g., collagen, fibrin, albumin to a wound site. However, allergic and immunological responses are common with these applications. Fifty percent of these cases are not resolved with a single application. More than twenty percent may not be resolved even after two applications.
Another treatment includes skin transplantation, which is performed for the most difficult cases. Skin transplantation is expensive, however, and may cost around $600-700 per application. A mesh of modified horse's collagen is used to support the new autologous tissue. The application is a difficult process that may take up to 20 days for cultivation of derma tissue, with the possibility to contaminate the sample, related to the dimensions.
Overall, methods and systems for preparing autologous fibrin glue or a solid-fibrin which is capable of regenerating tissue in a living organism are desired.
Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.